These findings, the first discovery of male-to-female oral sex in
bats, match prior studies revealing that
female bats perform fellatio, or oral sex, on male bats.

Scientists analyzed a colony of about 420 Indian flying foxes
(Pteropus giganteus) roosting in a single fig tree in
southern India, near the village of Nallachampatti. This
fruit-eating bat is one of the largest bats in the world.

Over the course of more than 13 months, using binoculars and a
video camera, researchers witnessed 57 cases of sex ― oral and
intercourse ― usually in the morning.

"Apart from humans, bats also exhibit oral sex as a courtship
behavior," said Ganapathy Marimuthu, a bat researcher at Madurai
Kamaraj University in India.

Initially, males groomed their penises to go erect before
approaching females. When they gently touched females with their
wings, females typically moved away, and males followed.
[ See
Video of Bats Having Oral Sex ]

When the females stopped moving, the males started licking the
females’ vaginas ― the act known as
cunnilingus. This foreplay may help arouse and lubricate
females, the researchers said.

Each case of cunnilingus typically lasted about 50 seconds. The
males then mounted the females for 10 to 20 seconds, and then
went back to cunnilingus for 94 to 188 seconds.

The researchers found that the longer the stints of cunnilingus
before mating, the more copulation was prolonged.

"It is possible that prolonged copulation enables
the mobility of sperm," Marimuthu told LiveScience. "Such
mobility of sperm increases the chances of conception."

The scientists also noted that males might perform cunnilingus on
females in order to clean off competitors’ sperm. Doing so could
help ensure their sperm, and not their rivals', impregnates the
females.

"In this context, cunnilingus would be maladaptive after mating,
as there is a risk of removing the male’s own sperm," the
researchers wrote. "Observation at close range is needed to find
out whether the male’s tongue enters the vagina or not."

The bat species found to perform male-to-female and
female-to-male oral sex were fruit bats. Oral sex may occur in
other species of fruit bats as well, Marimuthu suggested.

Marimuthu and Jayabalan Maruthupandian, also of Madurai Kamaraj
University, detailed their findings online March 28 the journal
PLOS ONE.